\hbox{%
  \def\classlist{David/Salomon, Michael/Downes, Frank/Mittelbach, David/Carlisle, 
    David/Kastrup, Heiko/Oberdiek, Till/Tantau, Donald/Arseneau, Joseph/Wright, 
    Hans/Hagen, Taco/Hoekwater, Hartmut/Henkel, Robin/Fairbain, Ulrike/Fischer, 
    Ulrich/Diez}
  % Let Will's processing function be \do:
  \def\do#1/#2,{%
    \ifx\do#1\else
      \noexpand\elt{\cpttrimspace{#1}}{\cpttrimspace{#2}}%
      \expandafter\do
    \fi
  }%
  \edef\classlist{\expandafter\do\classlist,\do/,}%
  \aftergroupexecute{\def\includelater{Will Robertson}}
  \expandafter\aftergroupexecute\expandafter{\expandafter\def\expandafter
  \somemasters\expandafter{\classlist}}
}
%\show\includelater
\show\somemasters
